Fast switch-off circuit for charging tube of battery management system

Abstract

Disclosed is a fast switch-off circuit for a charging tube of a battery management system, which includes a control circuit, a pull-down discharge circuit, and a discharge detection circuit. The control circuit synchronously switches on the pull-down discharge circuit when switching off the charging tube; and switches off the pull-down discharge circuit when detecting a trigger signal. The pull-down discharge circuit pulls down a gate voltage of the charging tube to a ground potential so as to discharge fast, when being switched on. The discharge detection circuit generates and transmits the trigger signal to the control circuit, when the gate voltage of the charging tube drops to a low-level threshold or a pull-down time of the charging tube reaches a time threshold, after the pull-down discharge circuit is switched on. The fast switch-off circuit ensures fast switch-off for a charging tube of a battery management system, while minimizing power consumption.

1 . A fast switch-off circuit for a charging tube of a battery management system, wherein a resistor with a resistance value which is greater than a preset resistance value, is connected between a gate and a source of the charging tube, wherein the preset resistance value is preset based on a power consumption requirement of the battery management system; wherein the fast switch-off circuit for a charging tube comprises a control circuit, a pull-down discharge circuit, and a discharge detection circuit; wherein:
 the control circuit is configured to synchronously switch on the pull-down discharge circuit, when switching off the charging tube; the control circuit is further configured to switch off the pull-down discharge circuit when detecting a trigger signal which is transmitted by the discharge detection circuit;   the pull-down discharge circuit is connected with the gate of charging tube; wherein the pull-down discharge circuit is configured to pull down a gate voltage of the charging tube to a ground potential for discharging, when the pull-down discharge circuit is switched on;   the discharge detection circuit is connected with the control circuit; wherein discharge detection circuit is configured to generate and transmit the trigger signal to the control circuit, when the gate voltage of the charging tube drops to a low-level threshold or a pull-down time of the charging tube reaches a time threshold, after the pull-down discharge circuit is switched on.   
     
     
         2 . The fast switch-off circuit for a charging tube of a battery management system according to  claim 1 , wherein the discharge detection circuit comprises a first voltage detection circuit, wherein a detection terminal of the first voltage detection circuit is connected with the gate of the charging tube, and an output terminal of the first voltage detection circuit is connected with the control circuit; the first voltage detection circuit is configured to compare a voltage at the detection terminal of the first voltage detection circuit with a reference voltage which corresponds to the low-level threshold, configured to output a low/high level when the voltage at the detection terminal is greater than the reference voltage, and configured to generate the trigger signal by flipping an output level of the first voltage detection circuit, when the voltage at the detection terminal is lower than the reference voltage. 
     
     
         3 . The fast switch-off circuit for a charging tube of a battery management system according to  claim 1 , wherein the discharge detection circuit comprises a first timer circuit, which is connected with the control circuit; wherein the first timer circuit is configured to start timing and output a low/high level when the pull-down discharge circuit is switched on, and configured to generate the trigger signal by flipping an output level of the first timer circuit, when a timed time reaches the time threshold. 
     
     
         4 . The fast switch-off circuit for a charging tube of a battery management system according to  claim 1 , wherein the discharge detection circuit comprises:
 a second voltage detection circuit, wherein a detection terminal of the second voltage detection circuit is connected with the gate of the charging tube; wherein the second voltage detection circuit is configured to compare a voltage at the detection terminal of the second voltage detection circuit with a reference voltage which corresponds to the low-level threshold, configured to output a low/high level when the voltage at the detection terminal is greater than the reference voltage, and configured to generate a first output signal by flipping an output level of the second voltage detection circuit, when the voltage at the detection terminal is lower than the reference voltage;   a second timer circuit, which is connected with the control circuit; wherein the second timer circuit is configured to start timing and output a low/high level when the pull-down discharge circuit is switched on, and configured to generate a second output signal by flipping an output level of the second timer circuit, when a timed time reaches the time threshold;   a combination processing circuit, wherein two input terminals of the combination processing circuit are connected with output terminals of the second voltage detection circuit and the second timer circuit, respectively; wherein the combination processing circuit is configured to output the trigger signal when detecting the first output signal or the second output signal.   
     
     
         5 . The fast switch-off circuit for a charging tube of a battery management system according to  claim 4 , wherein the trigger signal, the first output signal, and the second output signal, are all high levels, the combination processing circuit comprises an OR gate. 
     
     
         6 . The fast switch-off circuit for a charging tube of a battery management system according to  claim 4 , wherein the trigger signal, the first output signal, and the second output signal, are all low levels, the combination processing circuit comprises an AND gate. 
     
     
         7 . The fast switch-off circuit for a charging tube of a battery management system according to  claim 1 , wherein the pull-down discharge circuit comprises an electronic switch which is connected between the gate of the charging tube and ground, wherein a control terminal of the electronic switch is connected with the control circuit. 
     
     
         8 . The fast switch-off circuit for a charging tube of a battery management system according to  claim 1 , further comprising a drive circuit, wherein a controlled terminal of the drive circuit is connected with the control circuit, and the drive circuit is connected between the gate of the charging tube and an internal power supply, the control circuit is configured to switch off the drive circuit and synchronously switch on the pull-down discharge circuit, when the charging tube needs to be switched off. 
     
     
         9 . The fast switch-off circuit for a charging tube of a battery management system according to  claim 1 , wherein the charging tube is a MOSFET, a diode is connected between the gate and the source of the charging tube; wherein a positive pole of the diode is connected with the source of the charging tube, and a negative pole of the diode is connected with the gate of the charging tube.